1. Field of the Invention
The subject invention relates to the operation of gas turbine engines, and more particularly, to a control system for a turboshaft engine of a helicopter which includes a wide-band speed governor.
2. Background of the Related Art
In rotary wing aircraft, and more particularly, in helicopters, the main and tail rotors define the primary flight control surfaces for the aircraft. The rotor drive train for the main and tail rotor is coupled to the power plant which can have a single or twin engine configuration. Engine response, is therefore critical to the control of the aircraft. Even more critical to the control of the aircraft is fast fuel flow response to the engine. Thus, it is desirable to provide a rotor speed control system with a high bandwidth enabled by increased proportional and derivative power turbine governing gains. This can be achieved by appropriate filtering of the speed feedback signal.
It is also desirable to provide a rotor speed control system that has increased main and tail rotor resonant frequency attenuation as compared to prior art control systems. It would also be desirable to provide a rotor speed control system that eliminates the need for yaw and lateral cyclic load anticpation.
These and other desirable attributes are achieved as part of the subject invention by providing a high-order filter in the speed control loop of the engine control system disclosed herein.